This invention relates to an attracting nozzle control apparatus for a chip component mounting machine and, more particularly, to an improved apparatus and method for mounting components on a substrate.
A wide variety of types of apparatus have been proposed for picking up small components such as integrated circuits, resistors or the like, and mounting these components at an accurate location on a substrate. The components are normally picked up by a pick up device such as a vacuum pick up nozzle from a feeder station. When the components are picked up, their orientation relative to the pick up device cannot be accurately Controlled so as to ensure precision mounting. Therefore, it has been proposed to provide various ways in which the orientation of the component, as picked up by the pick up device, is determined, and then the mounting position is corrected to accommodate errors in the pick up location.
The co-pending application of Hiroshi Sakurai et al., entitled "Method For Mounting Components And An Apparatus Therefor," Ser. No. 08/073,741, filed Jun. 8, 1993, and assigned to the assignee hereof, discloses a method whereby optically it is possible to determine the orientation of a component picked up by the pick up device by rotating the component and measuring the projected length of the component in two (2) angular positions. From these measurements, the actual location of pick up can accurately be determined and the corrective factors calculated.
The apparatus and method shown in the aforenoted co-pending application Ser. No. 073,741 is particularly adapted when the component has a rectangular or square configuration. However, many components do not have such a configuration along their total height and this can give rise to certain problems in making the calculations and measurements necessary to determine the orientation. This may be best understood by reference to FIGS. 1 through 4, where FIG. 1 shows a type of component that can be easily measured with this type of apparatus, and FIGS. 2 through 4 show another type of component which could be measured by this apparatus if the component is correctly positioned in the sensing station.
Referring first to FIG. 1, a pick up and detecting station is identified generally by the reference numeral 11 and includes a pick up nozzle 12 that is adapted to pick up by means of a vacuum force, a small component, indicated generally by the reference numeral 13 which may be such an item as an integrated circuit, resistor, capacitor or the like. As will become apparent, the pick up nozzle 12 is movable in a vertical Z--Z axis and is rotatable about a vertically extending rotational R-axis.
The component 13 is picked up from a delivery station and then is raised into proximity with a sensing device, indicated generally by the reference numeral 14 which is comprised of a laser 15 that emits a plurality of parallel light rays L across a gap between the laser 15 and a detector 16 in the form of a capacitor coupled device (C.C.D.) that will receive a shadow from the component 13. The component 13 is then rotated by rotation of the nozzle 12 in a manner as described in the aforenoted co-pending application, Ser. No. 073,741, the disclosure of which is incorporated herein by reference. As noted in that application, this type of detecting apparatus 11 is particularly adapted for recognizing components having rectangular configurations in this method.
Although this type of device is very effective, its effectiveness is limited to the shape of the component which is picked up. Certain problems can be presented when the component picked up has, in addition to rectangular sections, other sections which are not rectangular, such as the component identified by the reference numeral 17 in FIGS. 2 through 4.
The component, indicated generally by the reference numeral 17, has a lower rectangular portion 18 which will actually be the portion that is mounted on the substrate (printed circuit board or the like). Extending upwardly from the rectangular section 18, is a cylindrical section 19 which may comprise a capacitor, resistor or other device having such a configuration. If the pick up nozzle 12 picks up the component 17 and positions it in the detecting apparatus 11 in an orientation as shown in FIG. 3 wherein the light rays L from the laser source intersect the rectangular section 18 rather than the cylindrical section 19, the device will be able to read the component 17 and develop the appropriate correction factors. If, however, the device 17 is picked up and is positioned in the detector section 11 as shown in FIG. 4, then a different situation will prevail.
It should be noted that with a conventional type of construction, the pick up nozzle 13 is moved to a fixed height in the detector section 14 and as may be seen from a comparison of FIGS. 1 and 4, the height of the nozzle 13 in FIG. 4 is the same as the height in FIG. 1 as would be the case with the conventional type of apparatus. When this occurs, the light rays L will strike the cylindrical section 19 of the component 17 rather than its rectangular portion and, accordingly, the device will be incapable of reading a correction factor because as the unit 19 is rotated, the area shadowed will remain of a constant width, although this shadow may shift slightly due to eccentric pick up.
It is, therefore, a principle object of this invention to provide an improved attracting nozzle control apparatus for a component mounting machine, and more particularly to an apparatus which can pick up components of irregular shapes or having portions of their shapes such that they cannot be read by the detector section and still providing an accurate detection signal.
It is a further object of this invention to provide an improved detecting apparatus and method for a component mounter using an optical scanner system that will ensure that the section of the component scanned is that which can be easily and correctly read.